South Carolina’s Lindsey Graham tops the list of Republican senators once thought to be vulnerable to a tea-party challenge this year who are now expected to easily win reelection.

The South Carolina primary is Tuesday, and a recent Clemson University Palmetto Poll found Sen. Graham leading a field of six challengers by a commanding margin: 40 points. In second place is state Sen. Lee Bright, polling at nine points. None of the other five challengers garnered more than 5 percent in the poll.

If Mr. Graham wins 50 percent of the vote in deeply Republican South Carolina on Tuesday, he will avoid a runoff and almost certainly secure reelection.

Mr. Graham, who has a campaign treasury of more than $11 million, has cemented his inevitability with traditional political grass-roots work; some shrewd behind-the-scenes maneuvering, including persuading potentially powerful opponents not to challenge him; and by taking on the tea party directly and arguing that an ultra-conservative Republican Party is not nationally competitive.

The senator, who has partnered with Senate Democrats on legislation, says that being a conservative doesn’t mean you can’t work with the other side to get things done.

South Carolina has an open primary system that allows independents to vote in the GOP primary. Unaffiliated voters have proven receptive to a more moderate message focused on trying to get something done in Congress. So Sen. Graham’s message of reasonableness could resonate with them–and help him top 50 percent on Tuesday.

Linda Killian is a journalist and a senior scholar at theWoodrow Wilson Center. Her most recent book is “The Swing Vote: The Untapped Power of Independents.” She is on Twitter:@lindajkillian.

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